The cationic trisacetonitrile complex [RuTp(CH3CN)(3)]PF6 has been obtained in 70% isolated yield by the reaction of RuTp(COD)Cl with NH4PF6 in boiling DMF/CH3CN. The CH3CN exchange kinetics has been studied by H-1 NMR as a function of temperature. The first-order rate constant of 1.2 x 10(-8) s(-1) (298 K) is very low compared to 5.6 s(-1) for the isoelectronic [RuCp(CH3CN)(3)]PF6, essentially because of a much higher energy of activation (37.2 vs 20.7 kcal mol(-1)).